django1/django/db/models/related.py

82 lines
3.5 KiB
Python

from collections import namedtuple
from django.utils.encoding import smart_text
from django.db.models.fields import BLANK_CHOICE_DASH
# PathInfo is used when converting lookups (fk__somecol). The contents
# describe the relation in Model terms (model Options and Fields for both
# sides of the relation. The join_field is the field backing the relation.
PathInfo = namedtuple('PathInfo',
'from_field to_field from_opts to_opts join_field '
'm2m direct')
class BoundRelatedObject(object):
def __init__(self, related_object, field_mapping, original):
self.relation = related_object
self.field_mappings = field_mapping[related_object.name]
def template_name(self):
raise NotImplementedError
def __repr__(self):
return repr(self.__dict__)
class RelatedObject(object):
def __init__(self, parent_model, model, field):
self.parent_model = parent_model
self.model = model
self.opts = model._meta
self.field = field
self.name = '%s:%s' % (self.opts.app_label, self.opts.module_name)
self.var_name = self.opts.object_name.lower()
def get_choices(self, include_blank=True, blank_choice=BLANK_CHOICE_DASH,
limit_to_currently_related=False):
"""Returns choices with a default blank choices included, for use
as SelectField choices for this field.
Analogue of django.db.models.fields.Field.get_choices, provided
initially for utilisation by RelatedFieldListFilter.
"""
first_choice = include_blank and blank_choice or []
queryset = self.model._default_manager.all()
if limit_to_currently_related:
queryset = queryset.complex_filter(
{'%s__isnull' % self.parent_model._meta.module_name: False})
lst = [(x._get_pk_val(), smart_text(x)) for x in queryset]
return first_choice + lst
def get_db_prep_lookup(self, lookup_type, value, connection, prepared=False):
# Defer to the actual field definition for db prep
return self.field.get_db_prep_lookup(lookup_type, value,
connection=connection, prepared=prepared)
def editable_fields(self):
"Get the fields in this class that should be edited inline."
return [f for f in self.opts.fields + self.opts.many_to_many if f.editable and f != self.field]
def __repr__(self):
return "<RelatedObject: %s related to %s>" % (self.name, self.field.name)
def bind(self, field_mapping, original, bound_related_object_class=BoundRelatedObject):
return bound_related_object_class(self, field_mapping, original)
def get_accessor_name(self):
# This method encapsulates the logic that decides what name to give an
# accessor descriptor that retrieves related many-to-one or
# many-to-many objects. It uses the lower-cased object_name + "_set",
# but this can be overridden with the "related_name" option.
if self.field.rel.multiple:
# If this is a symmetrical m2m relation on self, there is no reverse accessor.
if getattr(self.field.rel, 'symmetrical', False) and self.model == self.parent_model:
return None
return self.field.rel.related_name or (self.opts.object_name.lower() + '_set')
else:
return self.field.rel.related_name or (self.opts.object_name.lower())
def get_cache_name(self):
return "_%s_cache" % self.get_accessor_name()
def get_path_info(self):
return self.field.get_reverse_path_info()